地震發生後將蓄積在地層內的應變能釋出，至少可轉換成三個部份，震源輻射能量(ES)、碎形能和摩擦熱，地震發生後並不會將所有的應變能轉換成震波，大部分應變能在斷層錯動過程中因摩擦產生的熱而消散在地層中，只有少部分的應變能轉換成地震波而被觀測，而震源輻射能量的大小與斷層面上的狀態有關，因此，估算震源輻射能量能有助於瞭解地震的動態破裂過程。傳統評估震源輻射能量的方法主要利用震波積分所得，但對於大地震而言，有長的震源歷時和複雜的破裂，用傳統的方法常導致低估震源輻射能量。本研究先用多重破裂分析大地震中各個子破裂的震源歷時和地震矩(M0)，藉此估算每個子破裂的震源輻射能量，除能得到整得地震的震源輻射能量，也能進一步瞭解大地震的動態破裂型態。本研究為三年期計畫，第一年著重於方法的發展，務必使方法能穩定的計算，並分析數個大地震的多重破裂與其他研究比較，也著手研究逆推法的可行性。本研究也將利用此法重新調查1999 年台灣集集地震的震源輻射能量；第二年，利用本研究所提的作法繼續分析一些大地震，主要分析的地震為2001 年中國大陸崑崙地震、2002 年阿拉斯加地震等等，這兩個地震為走向滑移型態並且具有明顯的的單向破裂，本研究將近一步探討走向滑移型態的震源是否有較大的震源輻射能量；第三年，持續分析大地震的震源輻射能量，並總結先前分析的結果，以建立新的ES 與M0 的關係，也探討不同震源機制的ES 與M0 的關係是否有差別。
Strain energy is released during an earthquake, and is transformed into at least three parts, including radiated seismic energy (ES), fracture energy and heat due to friction. However, only low proportion of strain energy is transformed into ES, related to the state on the fault plane. Traditionally, the estimation of ES depends on the integral of squared seismic waves; however, it is difficult to estimate ES for large earthquakes due to the long source duration and complex ruptures during faulting. This study uses multiple event analysis to investigate sub-events for a large earthquake, and then obtains the source duration and seismic moment (M0) for each sub-event. Subsequently, this study estimates the ES of each sub-event from the derived source duration and seismic moment. Excepting getting the total ES, this study also can exhibit the variations in ES along the fault. This is helpful to understand the dynamic process of rupture. Basically, the duration of this proposal is designed to be three years. The program of the first year is to develop the procedure of estimating ES. This study also re-examine the ES of 1999 Chi-Chi earthquake. In the program of the second year, this study focuses on the estimates of ES for the 2001 Kunlun earthquake and 2002 Alaska earthquake, which rupture the fault with strike slip; then will discuss whether the strike-slip faulting has relatively large ES than other types of faulting. In the program of the third year, this study will establish a new relationship between Es and M0, and probe the variation of ES/M0 in various faulting mechanism.
